Water gas process



a. PEARSON, JR- 2,218,266

Oct. 15, 1940.

' WATERGAS rnocEss Filed July 19, 1938 INVENTOR hi5 PzgfisozvJie BY a2 7ATTORNEY Patented Oct. 15, 1940 v Q UNITED STATES PATENT OFFICE.

WATER GAS PROCESS Harry Brownley Pearson, In, New York, N. Y., assignorto Semet-Solvay Engineering Corporation, New York, N. Y., a corporationof New York Application July 19, 1938, Serial No. 219,914 Claims. (Cl.48-208) This invention relates to processes for making heater exerts adraft on the open stack valve, carburetted water gas and moreparticularly to particularly if the valve is placed in a stack of a anovel process for minimizing explosion hazards height not substantiallygreater than that of the v in water gas operation. superheater, andcauses air to enter through the 5 Within the past few years thecarburretted open stack valve in an amount sufilcient to form 5 watergas industry has adopted a noveltype of an explosive mixture with thecombustible gas water gas set involving a generator,"carburetor presentin the set. and superheater located in separate and detached I havefound that the formation of such exshells and connected in series, thetop of the plosive mixtures may be prevented in the operageneratorcommunicating with the base of the tion of such reverse flow sets duringthe startingcarburetor, and the top of the carburetor comup period bycausing a jet of suitable gas, prefmunicating with the top of thesuperheater so erably steam, to flow upwardly through the stack thatflow takes place up through the carburetor concurrently with the openingof the charging and down through the superheater, just the redoor foradmission of fuel into the generator, the

verse of the dircetion of flow in conventional carjet being at leastsufiiciently powerful to overcome l5 buretted water gas equipment. Thisnovel water the draft exerted on the carburetor and supergas set isdisclosed and claimed in United States heater by the escape of volatilesthrough the Patent No. 2,118,096, granted May 24, 1938, and chargingopening in the generator and that exwill be hereinafter referred to asthe Reverse erted by the superheater on the stack so that conflow watergas set. In the operation of such currently with the escape of volatilesevolved reverse flow water gas sets it was found that upon chargingthrough the charging opening of during the starting up periods pops orexplosions the generator, gas present in the carburetor and would occur,particularly within the carburetor superheater flows through the stackand entry of and at times in the superheater; Such pops or air throughthe stack is effectively prevented.

Z5 explosions are objectionable, not only because Thus, in accordancewith my invention, the opthey have a deleterious efiect upon therefracerations would involve cycles each consisting of tory lining andbrickwork within the carburetor an air blasting Step alter at ng withwater s and superheater, but also they indicate that exmaking stepsinvolving the passage of steam plosive mixtures of gas are formed'withinthe through the fuel bed, and at intervals,say, after set during thestarting-up period which upon every five or more cycles, the opening ofthe ignition might cause an explosion of suiiicient charging door, t echarging of fuel, which y intensity to destroy the water' gas set. Theprobbe coal or coke, into the generator, and the conlem of preventingthe'formation of such explosive current passage of steam through thestack mixtures within the set has received the attenthroughout thecharging operation, and while the tion of gas engineers, but, to myknowledge, no charging door is open, the steam pressure beingsatisfactory solution thereof has been found prior suilicient to createa draft in the stack greater y invention than the draft exerted on thecarburetor by the I have discovered the occurrence of explosions escapeof volatiles in the generator and also by in the water. gas set whileintroducing fuel into the downfiow superheater.

w the generator and during the starting-up period By the starting-upperiod as used in the o is caused by the tendency of the gases evolvedspecification and claimsismeant the period comin the generator uponcharging to rise through mencing with a cold set, one in which thetemthe open fuel charging inlet and create abackperature in thesuperheater is at atmospheric or draft through the carburetor,superheater and room temperature, or at a substantially higher stack,thus causing air to be drawn through the temperature due to long standbyperiod in which stack valve and form explosive mixtures in the no gashas been made, which temperature may set; the mixtures explode when theyare raised to be below 1,000 F., and terminating when the set ignitiontemperature by the hot refractory matehas been operated and until thetemperature at rial in the set. The tendency of the hot gases the top ofthe superheater is from l250 to 1300 evolved in the generator duringcharging to cause F. and at the bottom of the superheater is from so theentry of air into the set through the stack 1,000 to 1100 F. For astandard water gas set valve in the reverse flow set, I believe, isaughaving a generator, the internal diameter of mented by the draftexerted by the downfiow which is 10 feet and completely enclosed in asuperheater on the open stack valve, i. e. the natbuilding or otherhousing maintained at or about 5 ural tendency of. hot gas to risewithin the super- F., the period required for startin'g up a set is maybe about 2 hours for a set at atmospheric temperature or 30 minutes fora set in standby condition. In the case of a set in which thesuperheater is not housed within a building so that it is subjected toatmospheric influence, the starting-up period will obviously be muchlonger.

The process of this invention will be more fully described in connectionwith theaccompanying drawing, which discloses a preferred embodiment ofa water gas set in which the process may be carried out.

Referring to the drawing wherein like reference numerals indicate likeparts, there is shown a water gas set comprising a generator l, car-"buretor 2, and superheater 3. The carburetor is elevated so that. itsbase is substantially in the same horizontal plane with the outlet I ofthe generator and this outlet communicates with the inlet 5 to thecarburetor by a refractory lined passageway 3. Generator I is equippedwith the usual grate I for supporting a bed of fuel such as coal or cokeand a fuel charging opening 8 adapted to be closed by a suitable closure8' and is equipped with air inlets 9, H disposed beneath the grate andabove the top of the fuel bed respectively. The generator I has a steaminlet l2 disposed beneath the grate for supplying steam thereto. An oilspray l3 leads into the top of the generator above the fuel bed tosupply oil, which may be heavy oil such as Bunker C oil, during the gasmaking step, if desired.

-The carburetor 2 rests on a suitable structural steel support l4 andmaybe provided at its base with two or more layers of refractory materiall5 such as checkerbrick disposed on arches l8 positioned at the bottomof the carburetor. The portion of the carburetor above the oil spray isunobstructed throughout its horizontal cross sectional area. A watercooled oii spray I1 is located at the top of the carburetor, preferablyon the vertical axis thereof and is arranged to supply oil, which may begas oil or heavy oil such as residuum or Bunker 0 oil, to the carburetorduring the water gas making steps in a direction countercurrent to theupward flow of water gas through the carburetor. A header l8 providedwith downwardly directed pipes; I9 is arranged to supply secondary airto the base portion of the carburetor. The top ofthe carburetor has agas outlet 2| leading into the top of the superheater 3.

Checkerbrick 23, which may be of the type disclosed and claimed inUnited States Patent No. 1,927,834 granted September 26, 1933,conipletely fills the superheater 3 and rests on arches 24 disposed atthe base of the superheater. Gas outlet 25 of the superheater leads intoa vertical refractory lined stack 26 provided at its top with stackvalve 21; the stack valve may be opened and closed by any suitable meanssuch as a hydraulic cylinder (not shown) connected thereto by link 21'.The stack preferably is of a height somewhat greater than the height ofthe superheater so'that, as shown in the drawing, stack valve 21 isdisposed above the top of the superheater and constitutes the highestpoint of the set.

A conduit 23 leads from a point near the top of the stack 26 into avalve casing 29, which in turn communicates by pipe 3| with a wash box32. Backrun line or conduit 33 leads from the base of the generatorbeneath the grate into valve casing 29. The valve casing 23, aswellknown in this art, is provided with a three-way valve for reversing flowthrough the set, i. e. in

'above indicated, communicates with the superheater. The various valvesof the set maybe operated manually or automatically in any desiredmanner to.carry out the steps of the watergas cycle, e. g. the valvesmay be operated by hydraulic cylinders controlled from a control nest aswell known in this art.

In accordance with the invention, I provide a steam injector 31extending upwardly into the stack adjacent the upper end thereof andcommunicating through pipe 33 with a suitable steam supply, e. g. asteam boiler. The injector is equipped with valve 39 having an operatingmember 40 connected by pivoted link ll to the stack valve so thatopening and closing the stack valve results in simultaneous opening andclosing of the injector valve.

Steam pipe 33 is provided.

with manually operated valve 33' to shut off the supply of steam to theinjector when it is desired to open the stack valve without permittingsteam to flow through the injector.

The process of this invention may be carried out in the apparatus hereindescribed as follows: In starting up the cold set which may be at roomtemperature the fuel is first introduced into the generator. Aftercombustion of a portion of the fuel in the generator so that the fuelbed is heated to a temperature of 1200 F. air is passed through the fuelbed and the resultant blast gases passed up through the carburetor,secondary air admitted through l9 and the mixture burned as it flows-upthrough the carburetor and down through the superheater, the blast gasespassin through the stack valve 21 which is open connection 28 to washbox 32. This step may be of about two minutes duration.

The uprim may be followed by a backrun during which steam is introducedinto the stack through steam inlet 35 and is preheated as it fiowsthrough the stack, superheater and carburetor, backrun water gas beingwithdrawn from the base of the generator through backrun pipe 33. Thebackrun step may be of about one-half minute duration for the first fewcycles.

The blast, uprun and backrun, with the usual purges, constitute acomplete cycle. After about five or more cycles the fuel bed may bereplenished or, if desired, the fuel bed may be replenished more or lessoften. During the addition of fuel, in accordance with this invention,the

stack valve is open and steam admitted through 39 at a pressuresuflicient to create a draft which opening 3 so as to prevent the entryof air through sta k valve 21.

The temperature'in the superheater gradually rises during eachsucceeding cycle of the process. When the temperature at the top of thesuperheater reaches about 1300 F. and at the bottom of the superheaterabout 1100 F., i. e. when the end of the starting-up period has beenreached, it will generally not be necessary to continue the introductionof steam in the stack during the charging periods. Valve 39' in thesteam line 38 may then be closed so that on continued opera tion ofstack valve 21 valve 39 is operated by levers 40, 41, but no steamenters the stack because of the closing of valve 39. I

Since changes may be made without departing from the scope of theinvention, it is intended that the above description should beinterpreted in an illustrative and not in a limiting sense. I claim:

1. In the process of operating a carburetted water gas set involving agenerator containing a bed of fuel, which is replenished from time totime through a charging inlet located at the top of the generator, acarburetor and superheater connected in series, the top of the generatorcommunicating with the base of the carburetor and the top of thecarburetor communicating ,with the top of thesuperheater, so that flowtakes place up through the carburetor and down through the superheater,and a stack connected with the bottom of the superheater for flowtherethrough, which process comprises repeated cycles, each cycleinvolving the step of blasting the fuel bed with air and burning theblast gases in the carburetor and superheater, alternating with the stepof making water gas by passing steam through the fuel bed and passingthe resultant water gas through the carburetor and superheater, theimprovement which comprises at intervals between successive cycles ofsteps during the starting-up period of operation of the set, chargingthe fuel bed with fuel, and concurrently with the introduction of fuelinto the generator, placing'the stack in communication with theatmosphere and introducing a jet of gas upwardly into the stack duringthe charging of the generator.

2. In the process of operating a carburetted water gas set involving agenerator contaimng a bed of fuel, which is replenished from time totime through a charging inlet located at the top of the generator, acarburetor and superheater connected in series, the top of the generatorcommunicating with the base of the carburetor and the top of thecarburetor communicating with the top of the superheater, so that flowtakes place up through the carburetor and down through the superheater,and a stack connected with the bottom of the superheater for flowtherethrough, which process comprises repeated cycles, each cycleinvolving the step of blasting the fuel bed with air and burning theblast gases in the carburetor and superheater, alternating with the stepof making water gas by passing steam through the fuel bed and passingthe re-,

sultant water gas through the carburetor and superheater, theimprovement which comprises at intervals between successive cycles ofsteps charging the fuel bed with fuel, and concurrently with theintroduction of fuel into the gas upwardly into said stack whilereplenishing steam upwardly in the stack to create an upwardly draft inthe stack which draft more than counterbalances the draft caused by theescape of volatiles in the generator, thereby preventing entry of airinto the set through the stack during the charging of the fuel into thegenerator, and continuing the aforesaid introduction of steam into thestack during the charging periods until the temperature at the top ofthe superheater is from 1200 to 1300 F. and at the bottom of thesuperheater is from 1000 to 1100 F., and thereafter during repeatedcycles discontinuing the introduction of steam into the stack during thecharging periods.

3. In a process of manufacturing carburetted water gas in a water gasset involving a generator containing a bed of incandescent fuel adaptedto be replenished from time to time through a charging inlet located atthe top of the generator, a carburetor and a downflow superheaterconnected for now therethrough of water gas and blast gases from saidgenerator up through the carburetor and down through the superheater anda stack connected to said superheater and having,a closure adapted to beopened while said generator fuel bed is being replenished, theimprovement which comprises introducing a jet of said generator fuel bedthereby preventing gases rising in the generator creating backdraft inand drawing air into said set and forming explosive mixtures therein.

4. In a process of manufacturing water gas in a set involving agenerator containing a bed of incandescent fuel adapted to bereplenished from time to time through a charging inlet located at thetop of the generator, a downfiow superheater connected for flowtherethrough of water gas and blast gases from said generator downthrough said superheater and a stack connected to said superheater, theimprovement which comprises introducing a jet of gas upwardly into saidstack while replenishing said generator fuel bed, thereby preventinggases rising in the generator from drawing air into said stack andforming explosive mixtures in said set.

5. In a process of manufacturing carburetted water gas in a water gasset involving a generator containing a bed of incandescent fuel adaptedto be replenished from time to time through a charging inlet located atthe top of the generator, a carburetor, a superheater and a stackconnected in series for flow therethrough of gases from said generatorup through the carburetor, down through the superheater, and up throughthe stack, the improvement which comprises introducing a Jet of steamupwardly into the stack gases when replenishing=said generator fuel bedwhile the temperature of said stack gases is not high enough to impartsumcient buoyancy to the gases therein to counteract the tendency of thegenerator gases rising through the fuel charging inlet to create backdraft in the set, thereby preventing air from being drawn into saidstack

